scholarly journals ANALYTICAL APPROACH TO TECHNOLOGICAL SUPPORT OF FATIGUE LIMIT

2019 ◽  
Vol 2019 (3) ◽  
pp. 13-20
Author(s):  
Анатолий Тотай ◽  
Anatoliy Totay
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Analytical Approach ◽  
Critical Density ◽  
Cycle Number ◽  
Technological Support ◽  
Dislocations Density ◽  
Technological Impact ◽  
First Time

In the paper on the basis of the theory of metal plastic deformation there are obtained analytical de-pendences of dislocations critical density and cycle number up to destruction caused by factors technological impact upon the surface under working. For the first time in complex there are taken into account such physical characteristics as an effort, temperature and speed of deformation in the area of cutting and strengthening. A tie between such parameters of surface layer state as a steel grain size and dislocations density is defined.

scholarly journals Theory and practice of fatigue strength technological support in machinery

2018 ◽  
Vol 2018 (10) ◽  
pp. 38-42 ◽  
Author(s):  
Анатолий Тотай ◽  
Anatoliy Totay
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Theory And Practice ◽  
Surface Layers ◽  
Technological Support ◽  
Dislocations Density ◽  
Temperature Factors

On a basis of the theory of metal plastic deformation there are determined analytical ties between speed, power and temperature factors of machining with parameters of machinery surface layers defining their resistance to fatigue destructions. The paper reports the technological assurance options for resistance to fatigue by means of the control of such surface layer state parameters of machinery as dislocations density and a grain size of structure material.

Surface Layers' Real Structure of Metals Exposed to Inhomogeneous Thermal Fields and Plastic Deformation

2010 ◽  
Vol 163 ◽  
pp. 59-63 ◽  
Author(s):  
Zdenek Pala ◽  
N. Ganev ◽  
Jan Drahokoupil ◽  
Alexej Sveshnikov
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Real Structure ◽  
End Mill ◽  
Surface Layers ◽  
Thermal Fields ◽  
Mill Speed

Inhomogeneous thermal fields and plastic deformation are two basic phenomena present during surface creation and substantially determine future real structure of the surface layers. In the following, a closer look will be taken at some aspects connected with real structure of milled and ground steels. Impact of end-mill speed and thickness of removed layer on grain size, macroscopic and microscopic residual stress is discussed. Possibility of prestrained surface layer in ground steel has been examined on a set of five types of steels.

Ultrasonic Impact Treatment of Fine- and Coarse Grained Commercial Purity Titanium

2016 ◽  
Vol 1139 ◽  
pp. 12-15
Author(s):  
Rustam Hairullin ◽  
Anna Kozelskaya ◽  
Marina Kazachenok
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Electron Backscatter Diffraction ◽  
Coarse Grained ◽  
Commercial Purity ◽  
Ultrasonic Impact Treatment ◽  
Commercial Purity Titanium ◽  
Wide Range ◽  
Purity Titanium

The grain size effect on surface morphology, microstructure and mechanical properties of commercial purity titanium specimens subjected to ultrasonic impact treatment was studied. It was found by atomic force microscope that ultrasonic impact treatment of titanium specimens resulted in surface corrugation happens due to their severe plastic deformation. The profile height of the corrugated surface depends on the grain size of specimens and varies in a wide range. The thicknesses of a modified surface layer of fine-and coarse grained titanium specimens were studied. Electron backscatter diffraction (EBSD) analysis revealed that the plastic deformation was accompanied by twin and low angle boundary formation in the surface layer of titanium specimens. The effect of ultrasonic impact treatment on the microhardness of the surface layer of the specimens under study was investigated.

Surface Nanocrystallization of Low Carbon Steel Induced by Circulation Rolling Plastic Deformation

2005 ◽  
Vol 475-479 ◽  
pp. 133-136 ◽  
Author(s):  
Xin Min Fan ◽  
Bosen Zhou ◽  
Lin Zhu ◽  
Heng Zhi Wang ◽  
Jie Wen Huang
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Carbon Steel ◽  
Severe Plastic Deformation ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Surface Nanocrystallization ◽  
Average Grain Size ◽  
The Matrix

In this paper, the circulation rolling plastic deformation(CRPD) surface nanocrystallization technology is proposed based on the idea that the severe plastic deformation can induce grain refinement. The equipment of CRPD is designed and manufactured. A nanocrystallization surface layer was successfully obtained in a column sample of low carbon steel. The average grain size in the top surface layer is about 18 nm, and gradually increases with the distance from the surface. The hardness increases gradually from about 200HV0.1 in the matrix to about 600HV0.1 in the surface layer.

scholarly journals Structural Transformations and Mechanical Properties of Metastable Austenitic Steel under High Temperature Thermomechanical Treatment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 645
Author(s):  
Igor Litovchenko ◽  
Sergey Akkuzin ◽  
Nadezhda Polekhina ◽  
Kseniya Almaeva ◽  
Evgeny Moskvichev
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Temperature ◽  
Austenitic Steel ◽  
Structural Transformations ◽  
Initial State ◽  
Twin Boundaries ◽  
Metastable Austenitic Steel ◽  
Average Grain Size ◽  
Heating Up

The effect of high-temperature thermomechanical treatment on the structural transformations and mechanical properties of metastable austenitic steel of the AISI 321 type is investigated. The features of the grain and defect microstructure of steel were studied by scanning electron microscopy with electron back-scatter diffraction (SEM EBSD) and transmission electron microscopy (TEM). It is shown that in the initial state after solution treatment the average grain size is 18 μm. A high (≈50%) fraction of twin boundaries (annealing twins) was found. In the course of hot (with heating up to 1100 °C) plastic deformation by rolling to moderate strain (e = 1.6, where e is true strain) the grain structure undergoes fragmentation, which gives rise to grain refining (the average grain size is 8 μm). Partial recovery and recrystallization also occur. The fraction of low-angle misorientation boundaries increases up to ≈46%, and that of twin boundaries decreases to ≈25%, compared to the initial state. The yield strength after this treatment reaches up to 477 MPa with elongation-to-failure of 26%. The combination of plastic deformation with heating up to 1100 °C (e = 0.8) and subsequent deformation with heating up to 600 °C (e = 0.7) reduces the average grain size to 1.4 μm and forms submicrocrystalline fragments. The fraction of low-angle misorientation boundaries is ≈60%, and that of twin boundaries is ≈3%. The structural states formed after this treatment provide an increase in the strength properties of steel (yield strength reaches up to 677 MPa) with ductility values of 12%. The mechanisms of plastic deformation and strengthening of metastable austenitic steel under the above high-temperature thermomechanical treatments are discussed.

scholarly journals Finite element modelling of microstructural changes during equal channel angular drawing of pure aluminium

2021 ◽  
Author(s):  
Serafino Caruso ◽  
Stano Imbrogno
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Size Variation ◽  
Fe Model ◽  
Pure Aluminium ◽  
Continuous Dynamic Recrystallization ◽  
Research Activities ◽  
Hardness Change ◽  
Continuous Dynamic

AbstractGrain refinement by severe plastic deformation (SPD) techniques, as a mechanism to control microstructure (recrystallization, grain size changes,…) and mechanical properties (yield strength, ultimate tensile strength, strain, hardness variation…) of pure aluminium conductor wires, is a topic of great interest for both academic and industrial research activities. This paper presents an innovative finite element (FE) model able to describe the microstructural evolution and the continuous dynamic recrystallization (CDRX) that occur during equal channel angular drawing (ECAD) of commercial 1370 pure aluminium (99.7% Al). A user subroutine has been developed based on the continuum mechanical model and the Hall-Petch (H-P) equations to predict grain size variation and hardness change. The model is validated by comparison with the experimental results and a predictive analysis is conducted varying the channel die angles. The study provides an accurate prediction of both the thermo-mechanical and the microstructural phenomena that occur during the process characterized by large plastic deformation.

Computation on continuous grain refinement in AA1050 aluminum during repetitive tube expansion and shrinking technique

2015 ◽  
Vol 232 (4) ◽  
pp. 307-318
Author(s):  
H Jafarzadeh ◽  
K Abrinia
Keyword(s):  
Finite Element Method ◽  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Dislocation Density ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Half Cycle ◽  
Tube Expansion ◽  
Element Method

The microstructure evolution during recently developed severe plastic deformation method named repetitive tube expansion and shrinking of commercially pure AA1050 aluminum tubes has been studied in this paper. The behavior of the material under repetitive tube expansion and shrinking including grain size and dislocation density was simulated using the finite element method. The continuous dynamic recrystallization of AA1050 during severe plastic deformation was considered as the main grain refinement mechanism in micromechanical constitutive model. Also, the flow stress of material in macroscopic scale is related to microstructure quantities. This is in contrast to the previous approaches in finite element method simulations of severe plastic deformation methods where the microstructure parameters such as grain size were not considered at all. The grain size and dislocation density data were obtained during the simulation of the first and second half-cycles of repetitive tube expansion and shrinking, and good agreement with experimental data was observed. The finite element method simulated grain refinement behavior is consistent with the experimentally obtained results, where the rapid decrease of the grain size occurred during the first half-cycle and slowed down from the second half-cycle onwards. Calculations indicated a uniform distribution of grain size and dislocation density along the tube length but a non-uniform distribution along the tube thickness. The distribution characteristics of grain size, dislocation density, hardness, and effective plastic strain were consistent with each other.

Simulation of Grain Growth of Materials Produced by Severe Plastic Deformation

2011 ◽  
Vol 409 ◽  
pp. 597-602
Author(s):  
Yuichi Mizuno ◽  
Kenji Okushiro ◽  
Yoshiyuki Saito
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Dislocation Density ◽  
Severe Plastic Deformation ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Boundary Migration ◽  
Interface Energy ◽  
Diffusion Reaction ◽  
Field Methods

Grain boundary migration in materials under severe plastic deformation was simulated by the phase field methods. The interface energy and dislocation density on growth kinetics were simulated on systems of 2-dimensional lattice. .In inhomogeneous systems grain size distributions in simulated grain structures were binodal distributions. The classification of the solution of differential equations based on the mean-field Hillert model describing temporal evolution of the scaled grain size distribution function was in good agreement with those given by the Computer simulations. Effect of dislocation on thermodynamic stability was taken into consideration. Dislocation density distribution was calculated by a equation based on the diffusion-reaction equation.. Scaled grain size distribution was known to be affected by the dislocation.

scholarly journals A Dislocation-Based Theory for the Deformation Hardening Behavior of DP Steels: Impact of Martensite Content and Ferrite Grain Size

2010 ◽  
Vol 2010 ◽  
pp. 1-16 ◽  
Author(s):  
Yngve Bergström ◽  
Ylva Granbom ◽  
Dirk Sterkenburg
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Deformation Process ◽  
Volume Fraction ◽  
High Energy ◽  
Martensite Content ◽  
Plastic Deformation Process ◽  
Deformation Hardening ◽  
Dp Steels ◽  
Ferrite Grain Size

A dislocation model, accurately describing the uniaxial plastic stress-strain behavior of dual phase (DP) steels, is proposed and the impact of martensite content and ferrite grain size in four commercially produced DP steels is analyzed. It is assumed that the plastic deformation process is localized to the ferrite. This is taken into account by introducing a nonhomogeneity parameter, f(ε), that specifies the volume fraction of ferrite taking active part in the plastic deformation process. It is found that the larger the martensite content the smaller the initial volume fraction of active ferrite which yields a higher initial deformation hardening rate. This explains the high energy absorbing capacity of DP steels with high volume fractions of martensite. Further, the effect of ferrite grain size strengthening in DP steels is important. The flow stress grain size sensitivity for DP steels is observed to be 7 times larger than that for single phase ferrite.

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